Roll Out the Barrel

Everything old is new again; that’s one of the great things about the craft beer revival. Creative brewers feel quite free to take the elements of the past and build any kind of modern beer they can imagine. As you may know from flipping the pages of this fine magazine, the beer barrels are rolling out again, in the form of barrel-aged beer.

For at least a couple of millennia, wooden barrels served to ferment, transport and serve beer, as well as other beverages. One could even argue that without wooden barrels, beer might not be the omnipresent beverage of European history. The barrel’s a clever invention: oak or chestnut logs transformed into complex curved staves, which, when bound by willow or metal hoops, could hold liquid and even a bit of pressure. This must have been a dramatic, even magical breakthrough. No wonder songs were written about it.

The invention of the barrel is variously attributed to Bronze Age Celts, Vikings, or similar hairy-cloaked tribes. By Roman times, barrels were in use across a wide area of northern Europe. Barrels served admirably in a pre-industrial world, but the difficulty of cleaning and maintaining the ornery beasts led to their near-total demise by about 1950. Stainless steel perfectly suits the squeaky-clean nature of international lager, but for those of us who love the funky depths of a truly handmade beer, wood can offer that extra dimension.

Woody Characteristics

There are a number of reasons for this. First, wood is not flavorless. Wood contains chemicals that dissolve in the beer over time, adding woody, oaky or even musty flavors in some cases. Temperature swings cause the liquid to pump in and out of the wood, accelerating the process. Over a period of months or years, one of these substances—lignin—actually transforms chemically into vanillin, which is why vanilla notes are often found in whisky and other barrel-aged spirits.

Barrel wood is porous, which means the contents are exposed to air, creating the potential for oxidized flavors. These are generally regarded as defects in beer, but oxidized compounds give sherry and similar wines their wonderfully distinctive aromas. Porosity also means that there are lots of little nooks and crannies for microorganisms to hide, a fact that may be used to the brewer’s advantage or mitigated if necessary. Lambic and other sour beer brewers have developed a finely tuned method for shepherding the little critters to make beer for them, but there is such inconsistency that blending becomes a major part of the system. These sour beers are a complex subject that deserves a whole book, and, indeed, one is forthcoming from Brewers Publications. For the present, we are simply considering beers finished off in whisky barrels.

We Owe It All to Bourbon

The bourbon industry is America’s gift to the spirits world. The expensive charred-oak barrels may only be used once for aging bourbon, so when emptied, they are knocked down and shipped by the container load to places where Scotch, rum and tequila are aged. So cheap are they that they are often suffer the indignity of being cut in half and used for garden planters. They can also be used intact to age beer.

The first bourbon-aged beer I ever heard of was made by a group of suburban Chicago-area brewers who brought five 10-gallon batches of a strong imperial stout together to fill a fresh bourbon barrel. Six months later, they reconvened to bottle the beer. It was wonderful, although in their zeal to have enough whisky character, they added a bottle of the strong stuff, which definitely put the brew over the top. Shortly thereafter, Goose Island Beer Co. started experimenting with the style, one of the first commercial breweries to do so.

Aging Methods

This group method works fine, although it can be logistically challenging. A fresh barrel is best, as they get leaky when they dry out. A cool, dark place with some kind of sturdy stand or chocking is needed—the barrel will weigh about 450 pounds when full. And full it should be. Evaporation will occur, and you should have some beer handy for topping up or risk the dreaded vinegar-causing acetobacteria.

One to six months ought to do it, depending on how much whisky character you want. You could also run this as a solera system, meaning the barrel is never drained, but as a portion of beer is removed to be served, fresh beer is added. This can go on indefinitely with stronger beers, and the product can become incredibly complex.

You don’t need a barrel to get barrel-aged character. With just a little patience, you can create some sticks of bourbon-soaked wood suitable for aging beer, and end up with a bottle of custom-aged bourbon for your trouble.

Simply get hold of some American white oak and cut it up into a handful of finger-sized sticks or slats small enough to fit into the neck of a whisky bottle. With a propane torch or your brew stove, char them within an inch of their life. They should have a nice layer of char at least 1/16 of an inch deep. Remove about half the bourbon from a bottle of an inexpensive but reliable brand. Pull the sticks off the fire and drop them right into the bourbon. Top up the bottle and put it away for six months or so.

You might taste the whisky as it ages. I found it to be quite disgusting after a few weeks, but by six months, it acquires a smooth vanilla/oaky character. As soon as the bourbon gets to this delicious state and you also have beer ready to age, drain out the whisky and strain it through a coffee filter. Whisky aficionados will recognize this as “the good stuff,” and you should feel free to enjoy it. The sticks can then be dropped into a carboy of aging beer and left to do their thing.

What kind of beer is best for this treatment? As you might have guessed, this is not the best treatment for a pilsner; strong and dark is the rule. Imperial stout is the classic, and barley wine may also benefit. A super strong weizenbock, blonde barley wine or triple-bock might all be fun with a dab of whisky barrel flavor. Substitute Scotch for the bourbon in your aging experiment and you might create a deliciously inauthentic wee heavy. Irish whisky might do the same thing for a foreign export stout.

The possibilities really are endless and should amply illustrate the origin of the term, “barrel of fun.”